1. Technical Field
This invention generally relates to query governors in a computer database system, and more specifically relates to a database query governor for a multi-partition computer database system.
2. Background Art
Databases are computerized information storage and retrieval systems. A database system is structured to accept commands to store, retrieve and delete data using, for example, high-level query languages such as the Structured Query Language (SQL). The term “query” denominates a set of commands for retrieving data from a stored database. The query language requires the return of a particular data set in response to a particular query.
Optimization and execution of a database query can be a resource-intensive and time-consuming process. Further, the larger the database, the longer the time needed to execute the query. In order to prevent an excessive drain on resources, many databases are configured with query governors. A query governor prevents the execution of large and resource-intensive queries by referencing a defined threshold. If the cost of executing a query exceeds the threshold, the query is not executed. The query governor has a configuration file that determines the databases that an instance of the governor monitors and how it manages it.
Many large institutional computer users are experiencing tremendous growth of their databases. One of the primary means of dealing with large databases is that of distributing the data across multiple partitions. The partitions can be logical or physical over which the data is distributed. Prior art query governors have limited features when used in multiple partitions. Each partition has a query governor configuration file that determines how the query governor behaves for a given partition.
On partitioned computer systems in the prior art, the query governor is not able to effectively control the total use of resources across all the partitions. Without a way to more effectively govern queries in a partitioned environment, computer systems managers will continue to have inadequate control over database queries and their use of system resources.